free of salt
salt-free
free of sugar
sugar-free
Suffix -free means:
not containing the (usually bad) thing mentioned
Prefix un- means:
the opposite
Preffix non- means:
not
not dairy
nondairy
opposite of "healthy"
unhealthy
opposite of "true"
untrue
free of smoke
smoke-free
not fat
nonfat
opposite of "safe"
unsafe
not fiction
nonfiction